30-12-2015, 03:37 PM
REGULATION CHARACTERISTICS OF BUCK-BOOST CONVERTER
EXPT NO: 1
AIM:
To determine the closed loop response of the Buck-Boost converter and plot the regulation characteristics.
APPARATUS REQUIRED:
1. VSMPS-07A Trainer
2. Pulse patch chords
3. (0-30V) DC supply
4. CRO
FORMULA:
Output voltage V0 = (-D / 1-D)
Vs Volts Where
V0 = Converter Output Voltage
Volts Vs = Converter input voltage
volts D = Duty Cycle (ton / T)
THEORY:
The Buck Boost is a popular non-isolated, inverting power stage topology, sometimes called a step up/down power stage. The Buck boost power stage is chosen because the output voltage is inverted from the input voltage and the output voltage can be either higher or lower than the input voltage. However the output voltage is opposite in polarity from the input voltage. The Buck Boost converter circuit consist of MOSFET switch Q, inductor L, diode D, filter capacitor C and load resistor R.
CONNECTION PROCEDURE:
Connect P8 of PWM generator to PWM input of Buck-Boost converter circuit.
Connect P4 of Buck-Boost converter circuit to P7 of PWM generator.
Set switch SW1 to downward direction to select the closed loop operation.
Connect (0-30V) DC regulated power supply across P1 and P2 terminals
of the trainer module and set the voltage at 15 V.
EXPERIMENTAL PROCEDURE:
A) Line Regulation:
Switch ON the AC power supply and the power ON/OFF switch of the trainer kit.
View the carrier signal in CRO at T3.
Set the switch SW1 in downward direction.
Set the switch SW2 in downward direction.
View the PWM signal in CRO at T1.
Vary the Set voltage adjust POT from minimum to maximum and note down the ton and T values.
Set the PWM signal at desired duty cycle ratio (maximum 50%).
Switch ON the variable DC supply.
Vary the input voltage from (0-15) V and note down the corresponding output voltage across P5 and P6.
For each input voltage value tabulate the measured output voltage values.
Set the switch SW2 in upward direction and repeat the same procedure for Buck converter.